Mercury pollution is a global problem caused by coal combustion, gold mining, and other human activities, and has myriad adverse impacts to biodiversity. A new study by researchers at the Great Hollow Nature Preserve & Ecological Research Center (New Fairfield, CT, USA) and Western University (London, ON, Canada) has shown for the first time that exposure to methylmercury – the highly toxic form of mercury that most readily bioaccumulates up food webs – significantly alters the migration behavior of birds.